Study on preparation of activated mesocarbon microbeads/expanded graphite composites for electrical double layer capacitors

Electrical double-layer capacitors are now developing very fast and people put their eyes on the investigation about materials for electrodes, such as activated carbon with high surface area. One of the main ways to enhance the capacitance of porous carbonaceous materials was to improve the porosity and specific surface area. In this paper, a novel preparation process to increase the capacitance of activated carbon without changing pore structure was discussed and expanded graphite, which was usually used in the polymer material system, was used as the composite template for activated carbons. Expanded graphite with worm-like and symmetrical pores could provide good environment for activated carbon particles to touch with each other and the structure defects at the contacting sites were offset at a certain extent. The adsorption properties of activated carbons had not been changed much more after composite preparation but the capacitance of each composite had been improved greatly because that activated carbon particles were surrounded by plenty of graphite layers with better electrical conductivities. As a result, electrical double-layer capacitors made with composites had higher capacitance comparing with activate carbons themselves and had good performance under larger discharging currents.